White gold, 9ct diamond ring

This is the engagement ring my ex gave me about 5 years ago. I wore it for less than a year. It is white gold with a 9ct diamond and an unusual design. Size I. I believe it was round about £600 new. I have very slim fingers so it has been resized. I think it's a size I or J. It has a small imperfection on the underside where I dropped it but this isn't noticeable when on. No swaps. I'm asking for £300 or make me a reasonable offer :-) Thank you for looking xXx